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    SubjectRe: PostgreSQL pgbench performance regression in 2.6.23+
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    On Thu, 2008-05-22 at 11:05 +0200, Mike Galbraith wrote:
    > On Thu, 2008-05-22 at 13:58 +0530, Dhaval Giani wrote:

    > > Can you try with 2.6.26-rc? There is minimal load balancing for group
    > > scheduling till 25, which might explain the lack of scalability.
    >
    > I'm playing with it now, it's tweakable with migration cost. This
    > testcase is funky. It can't generate enough work to keep CPUs busy for
    > spit, and can't saturate my little quad with any kernel I've tried.

    Heh, watch this. No tweaking.

    (Nadia's ipc/idr patches are applied though, to see if the high end
    improves over previous runs with various kernels, and it does seem to.)

    2.6.26-smp x86_64
    1 10014.774797
    2 9791.395302
    3 10575.369296
    4 9763.183251
    5 10160.274262
    6 9893.174179
    8 9566.978464
    10 10294.456456
    15 9444.100540
    20 9137.878618
    30 8277.795499
    40 7925.824428
    50 7646.644285

    nail postgres to CPUs1-3
    nail pgbench to CPU0

    2.6.26-smp x86_64
    1 10900.959982
    2 15976.870604
    3 24661.322669
    4 25347.141780
    5 25893.815676
    6 26756.414839
    8 25399.018582
    10 26172.878669
    15 25542.082746
    20 25090.381828
    30 24270.301103
    40 23405.867336
    50 21926.223083





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